...Mitigated risk is the case here I think, with that mitigation being a consideration of foresight, planning, and experience/ability. But then, in all earnestness, why do you think that such a passage is beyond reasonable mitigation?

Organizing a boat move in the winter based on an open-ended plan responsive to the weather, reduces some of the risks...whether enough to make a trip prudent may deserve debate.

To organize a two-three day trip for a three day window, with fixed start and finish times, which ensures cutting judgement to make the schedule, is in my opinion a plan beyond reasonable mitigation.